As is known in the art, there is an openable body opening/closing device configured to open/close a back door of an automobile, using an extensible/contractible driving device which extends/contracts when driven by a driving unit.
Patent Literature 1 discloses a structure with an extensible/contractible driving device such as the device mentioned above configured to open a door of a refrigerator by electrical drive.
In regard to a technique relative to the present invention, Patent Literature 2 discloses a structure with a mold injection machine configured to move a screw in an axial direction by rotating the screw inside a screw cylinder so as to communicate or shut off a plasticizing part and an injection chamber.
In regard to another technique relative to the present invention, Patent Literature 3 discloses a structure with a master cylinder including a cylinder body and a piston, wherein the cylinder body includes a spring configured to apply spring force to the piston.